Master Docker Log Commands: Quick Tips for Efficient Debugging

When developing Docker‑based applications, effective log handling can greatly improve debugging efficiency. Below are common log operation techniques.

1. Show all logs

# Show all logs of a container
$ docker logs [OPTIONS] <CONTAINER>
# Show logs of all containers started with docker‑compose
$ docker-compose logs

2. Show real‑time logs

Similar to Linux tail -f filename, it streams the latest output to the screen.

$ docker logs -f <CONTAINER>

3. View log tail

Equivalent to tail -n 20 filename, displays the last 20 lines.

$ docker logs --tail 20 <CONTAINER>

4. Filter logs with grep

Example: find all logs containing “error”.

$ docker logs | grep error

5. View logs by time

Use --since to show logs after a specific timestamp, and --until for an end time.

$ docker logs --since 2018-09-25T12:01:46.452616Z <CONTAINER>
$ docker logs --since 2018-09-25T12:01:48.551341Z --until 2018-09-25T12:01:48.561714Z <CONTAINER>

6. Combine options

Options can be combined, e.g. tail the last 10 lines and filter for “info”.

$ docker logs --tail 10 <CONTAINER> | grep info
$ docker logs -f --since xxx --tail=10 <CONTAINER>

7. Write logs to a file

Redirect error logs to a file, or script the output for further processing.

$ docker logs -t <CONTAINER> | grep error >> logs_error.txt